Less of Our Light for More Star Light

Help Globe at Night shine a spotlight on light pollution

By J. Alex Knoll

With the moon waning through early morning skies, this weekend is a great opportunity to participate in the latest round of the Globe at Night program, which goes on through Tuesday, April 9. Relying on the observations of volunteers from all around the world, Globe at Night is gathering the most comprehensive data on light pollution. Citizen scientists including children and families, schools and civic groups participate by observing the faintest stars they can see within the constellation Leo the lion and recording their findings online.
“By locating and observing the constellation Leo in the night sky and comparing it to magnitude charts, children from around the world will learn how the lights in their community contribute to light pollution,” the Globe at Night website explains.
It’s easy to participate. Go to ­www.globeatnight.org to download your star chart of Leo and details and later to enter your observations. You’ll also need to know your latitude and longitude. A red-filtered flashlight will allow you to look at star charts without ruining your night vision. It takes 10 to 15 minutes for your eyes to fully adjust to the darkness. Other than that, head out to the darkest spot you can find at least an hour after sunset and look to Leo, comparing the stars you can see with those on the star chart.
One trick to increasing your count is looking out the sides of your eyes through your peripheral vision. The retina of our eyes has two types of cells: cones and rods. Cone cells are dense in the retina’s center, helping us discern color and detail in good lighting. In dim light, however, the cone cells are nearly blind. The edges of the retina, by contrast, are packed with rod cells, which are highly light-sensitive but color blind, registering only black and white.